HMC5883L — 3-Axis Digital Magnetometer / Compass IC

Overview

The HMC5883L is a 3-axis digital magnetometer IC manufactured by Honeywell. It uses Anisotropic Magnetoresistive (AMR) technology to measure both the direction and magnitude of Earth's magnetic fields (typically $0.3\text{ to }0.6\text{ Gauss}$ ) for electronic compass navigation in robotics, drones, and mobile devices.

Breakout boards (GY-271) include 3.3V power regulation and I2C level shifting. Note that most low-cost modules sold today contain the pin-compatible replacement chip QMC5883L by QST Corporation, which uses different I2C register addresses.

Quick reference


Module VCC	3.3 V to 5.0 V DC (onboard LDO)
Chip VDD / VDDIO	2.16 V to 3.6 V DC
Field range	$\pm 0.88\text{ Gauss}$ to $\pm 8.1\text{ Gauss}$ (default $\pm 1.3\text{ Gauss}$ )
ADC resolution	12-bit (5 milligauss field resolution)
Output data rate	0.75 Hz to 75 Hz (up to 160 Hz in continuous mode)
Communication interface	I2C (fixed address `0x1E` for HMC5883L / `0x0D` for QMC5883L)
Heading accuracy	1° to 2° (with proper hard/soft iron calibration)

Pinout

Standard GY-271 5-Pin Breakout Header

Pin	Name	Type	Description
1	`VCC`	Power	Supply voltage (+3.3 V to +5.0 V DC)
2	`GND`	Power	Ground (0 V)
3	`SCL`	Digital Input	I2C Serial Clock input
4	`SDA`	Digital I/O	I2C Serial Data line
5	`DRDY`	Digital Output	Data Ready interrupt pin (Active-HIGH)

Specifications

Parameter	Symbol	Min	Typ	Max	Unit	Conditions
Supply Voltage	$V_{DD}$	2.16	3.0	3.6	V	DC
Operating Current	$I_{DD}$	—	100	180	µA	Continuous measurement mode
Idle Current	$I_{idle}$	—	2	5	µA	Idle mode
Magnetic Field Range	$B$	$\pm 0.88$	$\pm 1.3$	$\pm 8.1$	Gauss	User selectable via Gain bits
Gain Sensitivity	$S_{gain}$	230	1090	1370	LSB/Gauss	$1090\text{ LSB/Gauss at } \pm 1.3\text{ G}$
Linearity Error	$NL$	—	0.1	—	% FS	Full scale
Operating Temp Range	$T_{OP}$	-30	—	85	°C

Register map (HMC5883L)

Address	Register	Access	Reset	Description
`0x00`	`CRA`	R/W	`0x10`	Configuration Register A (Samples averaged, Output rate, Measurement mode)
`0x01`	`CRB`	R/W	`0x20`	Configuration Register B (Gain configuration)
`0x02`	`MODE`	R/W	`0x03`	Mode Register (`0x00` = Continuous-measurement, `0x01` = Single-measurement)
`0x03`–`0x08`	`DATAX_H`..`DATAZ_L`	R	—	Data Output Registers (Order: X-MSB, X-LSB, Z-MSB, Z-LSB, Y-MSB, Y-LSB)
`0x0A`	`IRA`	R	`0x48`	Identification Register A (returns `'H'`)

Note

HMC5883L Axis Read Order: Notice that the register read order for HMC5883L is X, Z, Y (not X, Y, Z!). Register 0x03–0x04 is X, 0x05–0x06 is Z, and 0x07–0x08 is Y.

HMC5883L vs QMC5883L Differentiation

Feature	HMC5883L (Honeywell)	QMC5883L (QST Corp)
I2C Slave Address	`0x1E`	`0x0D`
`ID` Register (`0x0A` / `0x0D`)	Returns `'H'` (`0x48`)	Returns `0xFF` / `0x00`
Control Register	`0x02` Mode Reg (`0x00` = Continuous)	`0x09` Control Reg 1 (`0x1D` = Continuous)
Data Register Order	X_MSB, X_LSB, Z_MSB, Z_LSB, Y_MSB, Y_LSB	X_LSB, X_MSB, Y_LSB, Y_MSB, Z_LSB, Z_MSB

Wiring

GY-271 Module Pin	→	Microcontroller (Arduino Uno / ESP32)
`VCC`		`3.3V` (or `5V`)
`GND`		`GND`
`SCL`		`SCL` (A5 on Uno, GPIO22 on ESP32)
`SDA`		`SDA` (A4 on Uno, GPIO21 on ESP32)

Common mistakes

Using HMC5883L software library for QMC5883L clones: Most modern GY-271 breakout boards ship with QMC5883L ICs. Running an HMC5883L library on a QMC5883L chip will fail with I2C device not found at 0x1E. Run an I2C scanner script to check for 0x1E vs 0x0D.
Misinterpreting X, Z, Y register order on HMC5883L: Reading bytes in X, Y, Z order results in swapping the Y and Z values.
Ignoring Hard-Iron / Soft-Iron distortion: Nearby metal components, battery wires, or motors cause severe distortion. Calibration is required to map raw X/Y readings to a centered circle before calculating heading ( $\text{Heading} = \text{atan2}(Y, X)$ ).

Notes

Magnetic Declination angle must be added to the calculated magnetic heading to yield True North heading.

Interface	I2C
Supply	2.16–3.6 V
Package	16-pin LPCC (3 x 3 x 0.9 mm) / GY-271 Breakout Board